Initial Project Document Vacuum Tube Stereo Amplifier

Transcription

1 Initial Project Document Vacuum Tube Stereo Amplifier By Stephen Nichols, Jason Lambert, Rafael Enriquez Group 4 January 30,

2 Narrative Description Motivation The motivation for this idea is nostalgia. When one of the team members (Stephen, born in 1960) was young, all electronic circuitry was vacuum-tube based. Stephen prefers the sound of pure analog over vacuum tubes, and has always wanted to build a vacuum-tube based project, but with thoroughly modern features. This project will accomplish that goal, and provide invaluable project experience in analog and digital design for all team members. Goals Moderate audio power o enough to produce room filling sound for a typical living room Low noise Low distortion Relatively light weight o compared to similar devices produced in the pre-solid state era Modern touch screen based GUI control Specifications and Requirements Number of audio channels: 2 (stereo) Output Power Rating: 10 Watts per channel, RMS, peak Bandwidth: 50 Hz to 15 KHz flat within 3dB, rolling off to 6dB at 20Hz and 20KHz Total Harmonic Distortion: 0.5% from 100 Hz to 5 KHz Weight: 20 pounds max Special Requirements o Must be in a finished cabinet of contemporary design o Switching power supply o All audio parameters are digitally controlled Volume Balance 5-band Graphic Equalizer is preferred, but a simple Bass / Midrange / Treble is acceptable Input source switching o Touchscreen-based GUI (except for power switch) 2

3 An interesting graphical display that moves with the sound when simply playing The above specifications are very conservative. It is likely that the final circuit will provide better performance. Hardware Block Diagram 3

4 Software Block Diagram 4

5 Project illustration Figure 1 Created in Blender 5

6 Budget and Financing The budget for this project is $500, and will be entirely funded by Stephen Nichols Below is a brief list of the general components list that are planned to be included in the design. System Description Candidate Part # Mfr Vendor Cost Ea Qty Total Lead Time Signal Processor Digital Control Pots MCP41100 Microchip Tech DigiKey $ $19.32 Signal Processor Op-Amps TL-081 Texas Inst $ $6.00 Immediate Signal Processor D/A converters (P/O Microcontroller) Audio Preamp Preamplifier tube 12AU7 JJ Electronics thetubestore.com $ $21.90 Immediate Audio Power Amp Power Amp tube 6L6 JJ Electronics thetubestore.com $ $75.80 Immediate Audio Power Amp Impedance Transformer 125E Hammond Mfg DigiKey $ $ weeks Sound Detector A/D (P/O Microcontroller) $0.00 Sound Detector F/V converter LM2907 Texas Inst DigiKey $ $3.76 Immediate Touchscreen (P/O Display) $ bit microcontroller, 2 A/D ports, 4 D/A ports, 32 I/O ports, serial ports, Microcontroller LCD/LED driver AVR ATmega series Atmel DigiKey $ $8.00 TBD LCD Display TFT Color LCDisplay Module w/ touchscreen NHD M F ATXL# CTP 1 New Haven Display TBD $ $30.00 TBD Power Supply Low Voltage Supply LM2596 TBD Ebay $ $ week Power Supply Development High Voltage Supply Transformers, Diodes, Caps, etc TBD Skycraft $ $30.00 Immediate Debugger and Download Kit AVR Dragon Atmel DigiKey $ $54.00 Immediate Total $ *The above list is very conservative and is subject to change 6

7 Milestones Other Project Consideration The following project ideas were discussed and rejected: Automated Hand Write Simulator o Very little hardware all major components are available off-the-shelf o Would have been mostly a software effort o Rejected very early Indoor Tracking System o Preliminary discussions with some professors was not encouraging o Severe problems with the RF portion were anticipated performance would be poor 7

8 o Project was deemed to be more complex than could be developed in two semesters o Rejected very early Power Line Communication o Deemed to be of similar complexity to the vacuum tube amplifier o Deemed to consist of similar hardware vs. software component to the vacuum tube amplifier o Deemed to consist of similar analog and digital components to the vacuum tube amplifier Vacuum tube amplifier version Power Line Communication Parameters Power Line Commination Vacuum Tube Ampifier Use OF MCU 8 8 Hardware complexity assessment 7 7 Software complexity assessment 7 9 Analog and digital assessment 5 7 Overall complexity assessment 7 8 Overall feasibility assessment 8 7 Total Vacuum Tube Amplifier project chosen by consensus All critical parts found to be readily available Preliminary investigation for digital control of analog signal is very encouraging Stephen has extensive familiarity with the vacuum tube technology Power Line Communication project rejected by consensus A convincing demonstration scenario could not be determined 8